A Multi-Layered Membrane And A Method Of Preparing The Same

Abstract

There is provided a multi-layered membrane for separating components in an aqueous sample. There is also provided a method of preparing said multi-layered membrane, a method of separating blood plasma from a whole blood sample and a diagnostic device for separation of blood plasma from a whole blood sample.

1 - 27 . (canceled) 
     
     
         28 . A multi-layered membrane for separating components in an aqueous sample comprising:
 a porous layer for separating or retaining at least one component from said aqueous sample therein; and   an absorbent layer comprising a superabsorbent or absorbent material for removing liquid from said porous layer.   
     
     
         29 . The multi-layered membrane of  claim 28 , wherein said porous layer contains pores having an effective pore diameter in the range of 0.1 μm to more than 30 μm, or
 wherein said porous layer has a pore density in the range of 40% to 95%. 
 
     
     
         30 . The multi-layered membrane of  claim 28 , wherein said porous layer is a peelable layer, or
 wherein said porous layer is further modified to prevent blood clotting and reduce free radicals.   
     
     
         31 . The multi-layered membrane of  claim 28 , wherein said superabsorbent or absorbent material is selected from the group consisting of sodium polyacrylate, polyacrylic acid, alginic acid, starch, hydroxylethyl starch, modified starch, alpha cellulose, modified cellulose, chitosan, carboxylmethyl cellulose, montmorillonite, polyvinyl alcohol, polyethylene oxide, polyacrylamide, hydrolysed polyacrylonitrile, dextran, carboxylmethyl dextran, carbon nanotubes, silica, cotton, rayon, cellulosic pulp, synthetic pulp, bamboo silk, zeolite, glass fibers, polyester fibers, polyethylene fibers, fleece, and mixtures thereof. 
     
     
         32 . The multi-layered membrane of  claim 28 , further comprising a top layer comprising a peelable matrix layer. 
     
     
         33 . The multi-layered membrane of  claim 32 , wherein said top layer comprises a symmetric or an asymmetric membrane matrix. 
     
     
         34 . The multi-layered membrane of  claim 32 , wherein said top layer comprises a material selected from the group consisting of polyarylonitrile (PAN), polyethersulfone (PES), sulfonated polysulfone (SPSf), sulfonated polyethersulfone (SPES), cellulose acetate (CA), cellulose acetate butyrate, ethylcellulose, hydroxylpropyl cellulose, polyurethane, poloxamer polyols, poly(vinyl alcohol), poly(vinyl chlorine), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF) and combinations thereof. 
     
     
         35 . A method of preparing a multi-layered membrane comprising a porous layer and an absorbent layer, the method comprising the steps of:
 (a) providing a dope solution of a porous layer material in a solvent;   (b) casting the dope solution to form the porous layer via a method selected from the group consisting of electrospinning, non-solvent induced phase separation (NIPS), thermally induced phase separation (TIPS), vapor induced phase separation (VIPS), a combination of NIPS and TIPS (N-TIPS), and combinations thereof; and   (c) incorporating the absorbent layer adjacent to the porous layer via physical interaction or chemical treatment, wherein the absorbent layer comprises a superabsorbent or absorbent material for removing liquid from said porous layer.   
     
     
         36 . The method of  claim 35 , wherein:
 the porous layer material has a concentration in the range of 3.0 weight % to 10.0 weight %; and   the solvent has a concentration in the range of 90.0 weight % to 97.0 weight %, based on the total weight of the dope solution.   
     
     
         37 . The method of  claim 35 , wherein said porous layer material is selected from the group consisting of polyarylonitrile (PAN), polyethersulfone (PES), sulfonated polysulfone (SPSf), sulfonated polyethersulfone (SPES), cellulose acetate (CA), cellulose acetate butyrate, ethylcellulose, hydroxylpropyl cellulose, polyurethane, poloxamer polyols, poly(vinyl alcohol), poly(vinyl chlorine), polytetrafluoroethylene (PTFE), polyvinylidene difluoride (PVDF) and combinations thereof, or
 wherein said solvent is selected from the group consisting of N-methylpyrrolidone (NMP), dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), hexafluoroisopropanol, and combinations thereof.   
     
     
         38 . The method of  claim 35 , wherein when the method used in casting the dope solution to form the membrane is electrospinning, the time taken to collect the porous layer is in the range of 15 minutes to 120 minutes, or
 wherein when the method used in casting the dope solution to form the membrane is electrospinning, the porous layer is collected using a drum roller with a roller speed in the range of 70 rpm to 1000 rpm.   
     
     
         39 . The method of  claim 35 , wherein when the method used in casting the dope solution to form the membrane is selected from NIPS, TIPS or N-TIPS, the porous layer is casted using a casting knife with a height in the range of 50 μm to 500 μm. 
     
     
         40 . The method of  claim 35 , wherein said dope solution in step (a) further comprises an additive. 
     
     
         41 . The method of  claim 40 , wherein said additive is selected from the group consisting of methanol, ethanol, isopropanol, acetone, tetrahydrofuran, water, glycerol, ethylene glycol, and combinations thereof, or
 wherein during electrospinning, the weight percent ratio of the solvent and additive is in the range of 100:1 to 3:1.   
     
     
         42 . The method of  claim 35 , wherein during TIPS, a partial dope phase separation through VIPS process occurs, or
 wherein during TIPS, the porous layer material is PAN, the solvent is a mixed solvent of DMSO/water at 85/15% by volume, or the porous layer material has a concentration in the range of 40.0 mg/ml to 120.0 mg/ml.   
     
     
         43 . The method of  claim 35 , wherein when using N-TIPS, the casting dope solution is cooled in water at 25° C., or
 wherein when using N-TIPS, the porous layer material is PAN, or the porous layer material has a concentration in the range of 3.60 weight % to 6.50 weight % of the dope solution. 
 
     
     
         44 . The method of  claim 35 , further comprising the step of modifying said porous layer by physical or chemical means to contain specific binding sites for desired molecules. 
     
     
         45 . A method of separating blood plasma from a whole blood sample, comprising applying said whole blood sample to a multi-layered membrane, wherein said multi-layered membrane comprises a porous layer and an absorbent layer comprising a superabsorbent or absorbent material for removing liquid from said porous layer. 
     
     
         46 . The method of  claim 45 , wherein said whole blood sample is applied to a bottom surface of the porous layer where there are larger pores of greater than 30 μm pore size as compared to a top surface of the porous layer. 
     
     
         47 . A diagnostic device for separation of blood plasma from a whole blood sample, comprising a multi-layered membrane comprising a porous layer and an absorbent layer comprising a superabsorbent or absorbent material for removing liquid from said porous layer.